如何在nodejs中形成动态json数组？

Question

I have a set of values in my db. After reading that, my output will be like below.

FetchValues = 
  [{
   "Key": "123"
    "Value":"aa"
     "Type":"A"},
    {},
    {}
   ]

I need to form a dynamic json array like below after fetching the values from DB.

 {
  "A":{
   "123" : "aa"
  },
 {
  "B": {
    "124" : "bb"
  }
 }


 var Json = {}
for(k=0;k<fetchValues.length;k++)
{
  Json.push({ fetchValues[k].Type        
  : {
    fetchValues[k].Key : fetchValues[k].Value
    }
   })

But it gives error. Kindly help on this.

Answer 1

You may leverage destructuring syntax within Array.prototype.map() :

 const src = [{Key:"123",Value:"aa",Type:"A"},{Key:"124",Value:"bb",Type:"B"}], result = src.map(({Key, Value, Type}) => ({[Type]:{[Key]:Value}})) console.log(result)

 .as-console-wrapper{min-height:100%;}

Or (if your actual intention was to output an object, rather than array):

 const src = [{Key:"123",Value:"aa",Type:"A"},{Key:"124",Value:"bb",Type:"B"}], result = src.reduce((acc, {Key, Value, Type}) => (acc[Type] = {[Key]:Value}, acc), {}) console.log(result)

 .as-console-wrapper{min-height:100%;}

Answer 2

@Yevgen Gorbunkov 's answer is way better, but here's an approach using forEach :

const src = [{Key:"123",Value:"aa",Type:"A"},{Key:"124",Value:"bb",Type:"B"}];

let res = {};
src.forEach(element => res[element.Type] = { [element.Key]: element.Value });